According to a paper published in Annals of the Rheumatic Diseases, an individual's risk for developing gout has a genetic component. Gout, a form of inflammatory arthritis, is characterized by intense joint pain experienced without warning. This is accompanied by tenderness, swelling, and redness in the peripheral joints and is most often occurs at night. The big toe is frequently the joint that is most affected.
Gout is the result of the excess accumulation of uric acid in the bloodstream. Uric acid is traditionally expelled from the body through urine. However, there are occasions when the body produces too much uric acid or the kidneys are unable to rid the body of the correct amount.
This leads to the formation of urate crystals in the joints and surrounding tissues. Urate crystals are characterized by their sharp, needle-like appearance. They cause immense pain, inflammation, and swelling.
For decades, it was believed that the development of gout was almost entirely the result of a diet high in purine. Purine is found in organ meats, oily fishes, red meats, and a few vegetables including mushrooms and asparagus. As a result it was nicknamed the "disease of kings."
This was because rich men were the only people able to afford these foods in bygone eras. Now, however, scientists working with Dr. Chang- Fu Kuo, a practicing rheumatologist in Taiwan, at the University of Nottingham in the United Kingdom have completed research that indicates there is a genetic factor involved as well.
A gout linked genetic mutation, referred to as Q141K, causes a breakdown in the cellular pump that is necessary to clear acidic waste from the bloodstream. This includes uric acid. The mutation is simply the consequence of the replacement of one amino acid with another.
However, the new amino acid prevents the protein ABCG2 from directing uric acid out of the bloodstream and into the urine. This results in the accumulation of uric acid in the blood leading to the formation of urate crystals in the joints. Simply put, ABCG2 is necessary for ridding the body of uric acid. However, the genetic mutation prohibits it from functioning properly.
Dr. Kuo's study found that the risk of gout differs from men to women, but individuals with a family history have a greater likelihood of developing the ailment, regardless of sex. Physicians have long been aware that gout tends to cluster in families, but no population- based studies had been completed regarding this. Dr. Kuo did just this in Taiwan. Incidentally, Taiwan has one of the highest rates of gout in the world.
The survey found the following results.
- Men and women with a first-degree relative (parent, child, or sibling) diagnosed with gout were twice as likely to develop it as individuals in the general population.
- Having a twin that had been diagnosed with gout raised an individual's risk eightfold.
- Every additional first-degree relative with gout that an individual had increased their risk even further. This is referred to as "dose dependent."
- Men with a second-degree relative (grandparent, grandchild, aunt, uncle, niece, or nephew) were 1.25 times more likely to develop gout that those in the general population.
- Women with a second-degree relative were 1.4 more likely to develop it.